different ages, showing all these changes, may generally be found, and some 

 of them are represented in our figures (2, 3, 4, 5). The network, when 

 fully formed, is from au inch to an inch and a half in length, rarely more, 

 and from half to three-quarters of an inch wide, of an oblong or oval out- 

 line, obtuse at each end, and crenulate at the margin. The cells of the 

 rachis are cylindrical, about thrice as long as broad ; those of the pinnae 

 are somewhat clavate, shorter in proportion to their width, and those of the 

 pinnules scarcely longer than broad. All the nodes are contracted. The 

 stipes, in age, becomes coated with calcareous matter. The colour of the 

 network and of the young stipes is of a brilliant grass-green. The sub- 

 stance is soft and juicy, but the plant does not strongly adhere to paper in 

 drying. No fructification has been observed. 



At Plate VII. is represented the only other species of 

 Slruvea yet known to botanists, and the differences can readily 

 be seen by comparing the two figures. In the present Plate 

 some of the various stages through which the frond passes in 

 advancing to maturity are shown in the lower figures. By com- 

 paring these with similar stages in the development of Apjolinia 

 lalevirens (Plate V.), the close relationship of these Algae will 

 be apparent. In an early stage of growth, the Slruvea, as the 

 Jpjohnia, consists of a single, club-shaped, corrugated cell; 

 and the first change in either is by the development of a mi- 

 nute cellule, of a different character, at the apex of the first 

 cell. In each case this cellule becomes the basis of the charac- 

 teristic portion of the frond ; but in one, the Apjohnia, it grows 

 into a dendroid crown of trichotomous branches, and in the 

 other, the Slruvea, it developes a flat network. 



I regret that many of the duplicates of this plant distributed 

 by me are immature, the plant not having been quite in season 

 at the time of my visit to its only known locality. 



Fig. 1. A tuft of Struvea plumosa, consisting of fronds of different ages, — 

 the natural size. 2, 3, 4, and 5. Apices of young and older fronds: — 

 magnifie 



